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cmd/dist: make GOARM detection better compatible with thumb toolchain 

Fixes #4557.

R=dave, rsc
CC=golang-dev
https://golang.org/cl/6946078
This commit is contained in:
Shenghou Ma 2012-12-22 02:39:54 +08:00
parent 080d31cc50
commit c9eb6267df
1 changed files with 25 additions and 3 deletions
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28
src/cmd/dist/arm.c vendored
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@ -29,8 +29,19 @@ useVFPv3(void)
{
// try to run VFPv3-only "vmov.f64 d0, #112" instruction
// we can't use that instruction directly, because we
// might be compiling with a soft-float only toolchain
__asm__ __volatile__ (".word 0xeeb70b00");
// might be compiling with a soft-float only toolchain.
//
// some newer toolchains are configured to use thumb
// by default, so we need to do some mode changing magic
// here.
// We can use "bx pc; nop" here, but GNU as(1) insists
// on warning us
// "use of r15 in bx in ARM mode is not really useful"
// so we workaround that by using "bx r0"
__asm__ __volatile__ ("mov r0, pc");
__asm__ __volatile__ ("bx r0");
__asm__ __volatile__ (".word 0xeeb70b00"); // vmov.f64 d0, #112
__asm__ __volatile__ (".word 0xe12fff1e"); // bx lr
}
static void
@ -39,7 +50,18 @@ useVFPv1(void)
// try to run "vmov.f64 d0, d0" instruction
// we can't use that instruction directly, because we
// might be compiling with a soft-float only toolchain
__asm__ __volatile__ (".word 0xeeb00b40");
//
// some newer toolchains are configured to use thumb
// by default, so we need to do some mode changing magic
// here.
// We can use "bx pc; nop" here, but GNU as(1) insists
// on warning us
// "use of r15 in bx in ARM mode is not really useful"
// so we workaround that by using "bx r0"
__asm__ __volatile__ ("mov r0, pc");
__asm__ __volatile__ ("bx r0");
__asm__ __volatile__ (".word 0xeeb00b40"); // vomv.f64 d0, d0
__asm__ __volatile__ (".word 0xe12fff1e"); // bx lr
}
#endif